This invention relates generally to robotic tooling systems and more particularly to a passive tool changer which is adapted to permit a robot to change tools autonomously at the wrist joint which generally has a movable end-effector to which is attached a gripper or some other type of tool.
Robotic tool changers are generally known and generally fall into two classes, active and passive. An active type of system typically uses pneumatic or electrical actuators to make or break the connection between the two halves of the tool changer at the wrist joint. One example of this type of system is shown in U.S Pat. No. 4,676,142, entitled, "Adapter With Modular Components For A Robot End-of-Arm Interchangeable Tooling System", P. E. McCormick et al, which issued on June 30, 1987. A passive system, on the other hand, typically uses the robot's wrist motion to actuate an engagement mechanism. An example of this type toolchanger is shown in U.S. Pat. No. 4,512,709 entitled, "Robot Toolchanger System", D. M. Hennekes et al, which issued on Apr. 23, 1985.
Where a robot is intended to be used in zero gravity environments, such as outer space, tool changers which include pneumatic actuators are generally unacceptable. Toolchangers having electric actuators would also be normally unacceptable because large, redundant power trains and motors would result in an unwieldy system. While a passive tool changer such as shown in U.S. Pat. No. 4,512,709 could be utilized, it would inherently require a tool stowage assembly which intrudes significantly into the volume required for the tool, thus putting restrictive limits on tool size and shape. Also it relies on gravity to hold the tool securely in place when not in use, which is not acceptable for zero gravity environments. Furthermore, conventional tool changers do not lock tools down when not in use, nor do they provide a secure and fail safe hand-off of the tool from its parked or stowed position to an interface mechanism attached to the robot's wrist joint.
Accordingly, it is an object of the invention to provide an improvement in robotic tool changer mechanisms.
It is another object of the invention to provide an improvement in passive type tool changer mechanisms.
It is a further object to provide a tool change mechanism which performs a secure hand-off to and from the arm of a robot at any angle and in zero gravity environments.
It is still another object of the invention to provide a tool changing mechanism in which the hand-off operation may be interrupted or reversed at any time without any danger of the tool being unintentionally released or dropped.
And it is yet a further object of the invention to provide a tool changing mechanism which is designed so that it does not constrain the size and shape of the tool with which it is used.